^04 for dinnerware?

[Tww2005]

I am almost a complete beginner when it comes to ceramics. I took a few classes in school, but nothing in almost 15 years. I have been doing a lot of research, but I keep coming across conflicting information about how safe or reliable a ^04 glazed mug would be for use, not daily use, but still functional. 

[Sputty]

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[Min]

Hi and welcome to the forum 

Lots of people make and use lowfire functional pots. Having a well fitting glaze is really important, you want to avoid glazes that craze on lowfire. Microwaving can make the handles on lowfire mugs too hot to comfortably pick up if the clay absorbs water over time. You might want to glaze the mugs all over and fire them on stilts. What you are trying to do is avoid the clay from soaking up moisture. There are recipes for lowfire fritware but you likely don't want to get into making those.

[Pres]

Tww2005,

This discussion of Earthenware vs Stoneware and other higher firing clay bodies has been covered in other strands. A search in the Home page will bring up many discussions on the topic. In the long run, it may come to the understanding that all pottery needs to be made, glazed, and fired carefully. I work with  ^6 stoneware, and use a tight range ^5-^6 clay body that I have tested extensively, glazes that are for ^6 again tested on the clay bodies I use. I also test my ware with simple tests for leaching -vinegar sitting in the piece for a few days, I run pieces through multiple dishwasher runs and leave one sitting in dishwasher detergent for several days. I put pieces in the microwave and check them for heating up and other post heating cracking etc. Put them in the oven the same. Testing is of great importance. 

At the same time, techniques differ for the different ranges. I personally would never leave the base of an earthenware pot unglazed, as that would be an area for water to invade the clay weakening the glaze/clay fit. However, I know of several that do, and several that glaze the inside of the pot, not the outside, and those that do not glaze. It all depends on the use. 

Now as to glaze materials,

Myself, I have decided against anything in the shop that will have severe consequences for my own health. I know that my shop has a major hazard in dust, from silica. I do what I can, to keep that from getting too bad. At the same time I keep away from barium, lead, uranium, some other materials. Yes I use cobalt, chromium, and copper as coloring agents, and keep them in enclosed containers in a closed wall cabinet, carefully weighing them when mixing materials. In the long run, I place my personal health far and above the aesthetics of one color over another as I want to  live a long healthy life, and know that I can be messy, accidents do happen, and constant exposure to some materials could shorten that long life.

 

best,

Pres

[Min]

As the  op asked a question about "how safe or reliable a ^04 glazed mug would be for use" I don't think we need to get into (another) long discussion about the pro's and con's of lead glazes.  There are plenty of lowfire commercial glazes and recipes for lead free lowfire glazes available. If the op is interested in lead glazes there are numerous threads on that topic that can be searched for at the top of the page. 

[Sputty]

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[Mark C.]

 Earthenware vs Stoneware-I have found all my earthen ware did not last very long-meaning it broke easy over time. Just about all my cone 06 stuff is long gone now. Not true with high fired clays. I am using my cone 10 stoneware dinner set every day since 1976. A few chips on the feet but still ticking along.My earthen ware that is alive for the 70s is hanging on the wall not in use.

[Sputty]

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[Tww2005]

Thank you Sputty. I found the article interesting. 

 

[neilestrick]

17 hours ago, Sputty said:

On the other hand, Arbuckle and Pinnell make some very good points here:

earthenware (longer rant); pete pinnell on clay body strength

I particularly like Arbuckle's strong defence of earthenware. If only I could rant so cogently.

TL;DR - properly formulated, properly glazed, properly fired earthenware is (if anything) stronger than stoneware.

Stronger in the one type of test he performed, which was (if I remember correctly) pressing down on a bar of fired clay that was suspended between two points. It makes total sense to me, in that less dense/glassy earthenware clays can flex more before breaking. I'm not making the argument for any one side here, but that test doesn't necessarily have anything to do with the durability of a pot or its tendency to chip, which is a different kind of force, or the other types of physical stresses that may be put on a pot during daily use.

Low fire pots can function just fine, but glaze fit is extremely important. I have seen black moldy gunk growing under the glaze, because it has crazed and food stuff had soaked into the body and gone bad. In a vitrified pot it's not much of an issue, because even if the glaze is crazed, it would be very difficult for enough material to soak into the body to cause an problem. So do your homework and you won't have any problems.

[Sputty]

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[Pres]

I is probably just personal, but even this old guy with poor hearing prefers the ring of stoneware over the thunk of eathenware when rapped. 

 

 

best,

Pres

[preeta]

Tww why are you asking this question?

do you plan to become a professional potter? Or a hobbyist making for friends and family?

why 04? Because you want to lower your electric/gas bill? Or you only have access to a low fire kiln? 

Most studios normally do a cone 6 electric firing.  

Without you answering these questions I don’t know how to answer your question.  

There is a lot of great answers here.  For fellow potters.  Which can get overwhelming for those starting out.  

All I can say is perhaps the future is earthen ware. A lot of schools and potters are researching earthenware esp to see how it can handle restaurant use.  

Tom and Maggie Jaszczak Do soda fire at 03 but their ware is not meant for microwave or dishwasher use.  However they are safe for use.  

However I find the definition of “safe” around pottery to be cultural. 

[Tww2005]

Preeta, 

I have a low fire kiln (an Amaco ec55) Anything I make at the moment is for home, family, and friends. I just don't want to waste my time and kiln space creating a functional piece that actually isnt. I like doing decorative work, but would like to make other things too. 

[Callie Beller Diesel]

1 hour ago, preeta said:

 

Most studios normally do a cone 6 electric firing.  

 

In some locations, this is true.  In the Maritime provinces of Canada as a for instance, they have excellent local sources of earthenware and terra cotta clay, so not too many people mess with bringing in expensive import clays from the mainland. Earthenware and low fire clay use there is the norm, not the exception. Artists like Walter Ostrom, Joan Bruneau and Mariko Paterson all make most excellent functional ware that is fired to cone 06-04. They take advantage of the colour options that are available at low temps: the pinks, teals, yellows and greens that burn out in hotter kilns are all good reasons to work in the earthenware range.

I think it's easy when you work at high temperature to just rely on heat to cure all ills. It can lead to lazy thinking in some beginners. I agree with Linda in the article that regardless of the temperature, you have to know your materials and your chemistry in order to make wares that are long-term durable, and that it is possible to do with testing.